In node-red how to store tcp data in session context

In node-red tcp server I am getting username for the first time for authentication. So, I need to store for the session. So, for the second packet I just want to send the data with the user name appended which is sent earlier for authentication to mqtt broker. So, how can I store the username first and send the username for next data onward in node-red tcp server. The users can be any number who is connecting and sending data .